Showing papers on "Quantum well published in 1977"

Free Electron Lasers

Abstract: Lasers based on the stimulated emission of radiation by free electrons in a spatially periodic magnetic field offer a unique potential for tunable operation at high power and high efficiency. Substantial advances have been made recently in the theoretical analysis of this class of device and in the operation in our laboratory of a 10 μ free electron laser amplifier. These results and the implications for the design of a practical device will be reviewed.

In‐cavity hot cell for use with sequence CO2 lasers

Abstract: A technique is described for approximately doubling the number of laser lines obtainable from cw CO2 lasers. This technique involves the use of an in‐cavity cell containing hot CO2. Construction details are given of a suitable cell which attains gas temperatures as high as 500° C.

Waveguides for submillimeter-wave lasers

Abstract: A review of the development and the present state of the art of waveguides for submillimeter-wave lasers is presented. Theoretical and experimental aspects of waveguides for longitudinally and transversely excited as well as for optically pumped lasers are discussed. This is followed by a comment on investigations of periodic waveguide structures for distributed feeback submillimeter-wave lasers.

Correlation between the optical output characteristics and the time-dependent behaviour of semiconductor lasers

Abstract: Various optical output characteristics of double-heterostructure lasers have been examined, together with the response of laser emission current pulses. Correlations between the two have been observed.

Novel double-heterostructure lasers

Abstract: In this paper we describe the preparation and characterization of two novel kinds of double-heterostructure (DH) lasers which combine both the Burrus LED and oxide-stripe laser technologies. Laser emission from one of the devices (Type I) emerges from a pair of holes which are etched through the substrate to expose the n-GaAlAs first confining layer. The n-GaAlAs/air interface forms the mirrors of the resonant optical cavity and the laser emission is perpendicular to the gain region, (active layer of the DH). In the second device (Type II) the resonant cavity is formed between the n-GaAlAs/air interface and a

Amplification of UV picosecond pulses in high pressure XeF discharges

Abstract: At present, C 0 2 and atomic iodine are the only two lasers with demonstrated properties that make them candidates for a repetitivelypulsed laser fusion system. However, there are uncertainties for each of these lasers which must be evaluated to project large system performance. At Sandia, we are conducting experiments to evaluate properties oftheatomiciodine laser pertinent to its possible use in a laser fusion system. The results presented below were obtained from the SAIL-1 facility, which consists of an actively modelocked oscillator, a 1-cm diameter x 1Wcm long preamplifier and a 7.5cm diameter x 3 5 k m long final amplifier.’ The subnanosecond atomic iodine oscillator developed by Jones et al.’ has been modified to produce pulses with more reliable beam quality. This is accomplished by pumping faster and allowing the oscillator to gain-switch 6 psec after flash initiation. Therefore lasing occurs before the onset of the gas dynamic disturbance which occurs in the lasing volume at 10 psec after flash initiation. The beam profile was photographed 20 m from the oscillator and is nearly Gaussian with no hot spots. Also, data from a shearing plate interferometer indicate that here is no detectable phase distortion across the wave front and that the oscillator output is nominally diffraction limited. The reproducibility of the SAIL-I oscillator (an important consideration for laser fusion) is good, approximately & 10% in amplitude and pulse width. Temporal pulse distortion can occur in an iodine laser amplifier because of gain saturation and/or insufficient bandwidth for short pulse amplification. Data were obtained which demonstrate the range of pulse distortion versus bandwidth in an unsaturated amplifier. Working with sufficient bandwidth to give true pulse amplification, the pulse distortion due to gain saturation was characterized. In both cases, the data were used to check a computer code which models pulse propagation in an iodine amplifier. Good beam quality and focusability are essential for laser fasion. In an iodine amplifier. the beam quality can be affected by gas dynamic disturbances or anomalous dispersion in a saturated amplifier. Using a shear plate interferometer amplified pulses from the preamplifier were found to have < 1/2 wave phase distortion. Calculations indicate that this amount of phase distortion will not affect the focusability. In addition, data were obtained with the shearing plate interferometer for a saturated beam in the large amplifier. Also, the beam profile of the output from the large amplifier was photographed at various degrees of focus.